Search

The Vendée Globe is the world’s most famous solo, non-stop, unassisted sailing race. The Institute of Marine Sciences and the Barcelona Ocean Sailing Foundation installed a MicroCAT on the One Ocean One Planet boat. The skipper, Dídac Costa, completed the round trip in 97 days, from 8 November 2020 to 13 February 2021, providing one measurement of temperature and conductivity every 30 s during navigation. More than half of the ship’s route was in the sub-Antarctic zone, between the tropical and polar fronts, and it passed through areas of oceanographic interest such as Southern Patagonia (affected by glacier melting), the Brazil–Malvinas confluence, the Southern Pacific Ocean, and the entire Southern Indian Ocean. This sailing race gave a rare opportunity to measure in-situ sea surface salinity in a region where satellite salinity measurements are not reliable. Due to the decreased sensitivity of brightness temperature to salinity in cold seas, retrieving sea surface salinity at high latitudes remains a major challenge. This paper describes how the data are processed and uses the data to validate satellite salinity products in the sub-Antarctic zone. The sailing race measurements represent surface information (60 cm depth) not available from drifters or Argo floats. Acquiring measurements using round-the-world sailing races would allow us to analyse the evolution of ocean salinity and the impact of changes in the ice extent around Antarctica

The RETRO-BMC oceanographic cruise was designed to characterize the spatial structures and variability of the Brazil-Malvinas Confluence (BMC) region. The cruise was carried in April 2017 on board the R/V Hespérides, departing from Ushuaia (Argentina) and arriving to Santos (Brazil). There were a total of 33 hydrographic stations, carried out between 13 and 25 April 2017. All stations were offshore from the continental platform and within 42ºS-36ºS and 58ºW-52ºW. Conductivity-temperature-depth (CTD) data were obtained with a SeaBird 911 Plus multi-parametric probe, with redundant salinity and temperature sensors, and additional dissolved oxygen (SBE-43) and fluorescence and turbidity (Wetlabs AFL-NTU-RTD) sensors. Water velocity data was obtained at the stations with a lowered acoustic Doppler current profiler (LADCP) and along the ship’s track with the vessel-mounted ADCP (VADCP). During the entire ship’s track inside the study region, the VADCP gathered velocity data in low-range mode (one velocity profile every 2 min between about 20 and 800 m at 8-m depth bins) and a thermosalinograph gathered salinity and temperature data (every 5 s at a depth of 5 m). The LADCP was attached, together with the CTD, to a 12-liters 24-Niskin-bottle rosette that was used to gather water samples at discrete depths, which were frozen and later analyzed to determine the concentration of inorganic nutrients. In addition, two high-resolution three-dimensional surveys were carried out at the Confluence front with a SeaSoar covering the area between 40.6-39.0°S and 55.6°W-53.8°W. The first transect was completed between the 16 and 17 April, 46 hours covering 620 km, while the second sampled 751 km between the 19 and 21 April 2017, during 52 hours. The SeaSoar was equipped with a SeaBird 911 CTD with the same sensors as in the hydrographic stations, and recorded data in a sawtooth pattern between 5 and 360 m, with a horizontal spacing between apogees of 4 km. Finally, five subsurface drif